Existing tungsten halogen lamps, such as the common, medium two-pin lamp, are typically comprised of a lamp capsule including a sealed envelope of a vitreous material having a bulb portion and a press-seal at one end thereof, and a base secured to the envelope for supporting the press-seal thereof. One presently-employed base is comprised of a metal shell fitted with a ceramic insulator at the bottom thereof. The ceramic insulator in turn supports two connector pins. This type of base with a metal shell is used for a number of lamp types ranging in wattage from 500 to 1000 watts, and voltages as high as 240 volts. Lamps of this type have widespread use in studio, theatre, and television lighting applications.
Several problems have been encountered with these metal/ceramic lamp bases. It is difficult to align the capsule and base on the same center line. Additionally, there exists a potential for short-circuiting the metallic base shell to the wire/fuse electrical wiring between the envelope and pins. With the metal shell there is also a possible breakdown of the shell at higher temperatures and voltages. Lastly, the appearance of the product may appear unsightly to a prospective customer.
Tungsten halogen lamps are also known in which the base is constructed of a ceramic material. In this regard, see U.S. Pat. Nos. 3,974,370, 4,243,907 and 4,568,854. However, in all of these ceramic base constructions, the base is formed so that it will accommodate a sealing cement between the base and the press-seal (such that the cement almost totally surrounds the press-seal). These ceramic base lamps, although having solved the aforementioned short-circuiting and breakdown problems are still characterized by difficulty of alignment between the capsule and the base.
Accordingly, it is believed that a lamp base which overcomes the aforementioned disadvantages of existing bases would constitute an advancement in the art.